1. Field of Invention
The present invention relates to a honing tool for working several bars arranged coaxially in series and with different diameters, wherein the honing tool includes several cutting bar groups arranged coaxially in series, wherein a diameter of a cutting bar group, which diameter is formed by radially extendable cutting bars, differs from the diameter of at least one other cutting bar group. Furthermore, the invention relates to a method for working several bores arranged coaxially in series by a honing tool and a control device of a honing machine.
2. Brief Description of Related Art
Honing is a machining, fine working method that can be used in a versatile manner and with the aid of which among other things the accuracy of the dimension and of the position of cylindrical bores is improved.
Internal combustion engines of motor vehicles have bearing channels for the crankshaft, camshafts and/or compensation shafts. Bearing seats or bearing webs for the sliding bearings or roller bearings are arranged in these bearing channels. These bearing seats must be arranged coaxially to each other, i.e., they have a common central axis.
In the context of the invention the bearing seats are also designated as bores or as bore sections. A cylindrical bore with a constant diameter is designated as a through bore; examples for this are the bores 17a and 17b in FIG. 5.
A cylindrical bore with a shoulder and the resulting jump in diameter is designated as a stepped bore; an example for this are the bores 17c and the associated shoulder 17d in FIG. 5.
The axial distance of the individual bearing seats is frequently greater than its diameter. Therefore, the bore sections can only be worked by a relatively thin and long tool. These geometric border conditions make it difficult to achieve a good accuracy of the measurement and position of the bearing seats.
For example, DE 196 34 415 A1 shows a tool for working main bearing bores in crank housings with an upper and a lower guide range which can be adjusted to different diameters. A cutting range lies between the guide ranges in which deliverable bars with cutting coating are arranged. A lower guide range is adjusted to the measure of the pre-working of the bore and an upper guide range is adjusted so that it rests on the previously working bore. This tool is designed for the working of through bores with a unified diameter. No stepped bores can be worked with it.
DE 44 39 381 shows a tool for working individual bearing webs with a bearing seat of the crankshaft support of an internal combustion engine. A first, upper bearing web has a greater diameter than the bearing webs arranged underneath it. In order to work the bores the tool is constructed in a stepped shape, wherein the corresponding cutting bar groups are arranged axially in series and are adapted to the diameter of the bores. As a result, a coaxial working of lower, smaller bores and of the upper, larger bore is possible. All bores of the individual bearing webs must be constructed as a through bore.